The primary objective of this study is to determine whether Multiple Sclerosis patients differ from normal controls in their neuroendocrine response to serotonergic stimulation and to examine whether these differences are related to depression, suicidal ideation and behavior, length of illness and functional impairment. By comparing the serotonin- induced neuroendocrine response of depressed and non-depressed MS patients with healthy controls, the proposed study will examine whether serotonergic deficits are inherent in MS or a byproduct of depression....